A charged particle radiation device, such as a transmission electron microscope, a scanning electron microscope or an electron beam lithographic device, uses an electron gun to obtain an electron beam. There are a variety of electron guns including a cold field emission electron gun and a Schottky electron gun; each causes an electric field to concentrate on the tip of an electron beam by applying a high positive voltage (extraction voltage) to an extraction electrode opposed to an electron source having a sharp tip, and causes an electron beam to be emitted. The configuration of the electron gun is disclosed in, for instance, Patent Literature 1 through 3.